There is presently no cost effective compact solution for the motorist to check vehicle wheel alignment toe angle. Commercial gauges are very expensive and most laser optical versions are based on the method described in GB1395882. They all use a basic principle of calibration to the parallel plane and rely on maintaining this calibration when used to check a vehicle's wheels deviation from the parallel plane.
All existing laser optical methods use two planar gauges, consisting of long spans that are single strong parts, to maintain calibration. They are heavy and difficult to store. These spans are the main obstacle to providing the benefit of a compact solution for home storage. Splitting of the spans creates a fundamental problem with existing methods because span parts cannot be relied on to fit together with the same straightness every time thus creating a high risk of a user using un-calibrated apparatus and getting inaccurate results. Commercial gauges are also prone to easy mis-calibration, being pre-calibrated by placing gauges face to face. Over this short distance any small misjudgement is multiplied many times when gauges are moved far apart on a vehicle. Some more expensive gauges use a rig to hold gauges further apart to minimise this risk. This is better but does not provide a low cost, compact solution.
The spans require further components to access the plane of the wheels and devices at one end to facilitate the intended method. Some stand on the floor and are provided with vertical arms and others are arranged for hanging on or clamping to the wheels. Height, width and level adjustment require separate technical features.